<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta http-equiv="X-UA-Compatible" content="IE=edge" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
   
  </head>
  <body>
    <div id="app">
      <button @click="doubleNum = 100">修改doubleNum</button>
      {{num}}
      <br>
      {{doubleNum}}
    </div>

    <script src="./vue.global.js"></script>
    <script>
      const { createApp } = Vue;
      const app = createApp({
        data() {
          return {
            num: 10
          };
        },
       
        // 新增 computed 属性
        computed: {
          doubleNum: {
            get(){
              return this.num * 2;
            },
            set(val){
              console.log('setter触发', val);
              this.num = val / 2;
            }
          }
        }
      });
      app.mount("#app");
    </script>
  </body>
</html>
